U.S. patent number 6,670,006 [Application Number 09/381,628] was granted by the patent office on 2003-12-30 for epoxy resin composition for frp, prepreg, and tubular molding produced therefrom.
This patent grant is currently assigned to Mitsubishi Rayon Co., Ltd.. Invention is credited to Akira Agata, Kazuya Gotou, Yukio Nishimoto, Masahiro Sugimori, Masato Taguchi.
United States Patent |
6,670,006 |
Sugimori , et al. |
December 30, 2003 |
Epoxy resin composition for FRP, prepreg, and tubular molding
produced therefrom
Abstract
The present invention relates to an epoxy resin composition for
FRP that will be used for fishing rods, golf club shafts, and the
like, a prepreg that is an intermediate material made up of an
epoxy resin composition combined with reinforcing fibers, and a
tubular molded article obtained using it. The epoxy resin
composition for FRP of the present invention comprises (A) a
bisphenol A-type epoxy resin, (B) an epoxy resin having oxazolidone
rings, and (C) a curing agent. By using the epoxy resin composition
for FRP of the present invention, a prepreg quite excellent in
handleability and a tubular molded article improved in flexural
strength in the longitudinal direction and crushing strength in the
diametrical direction can be obtained.
Inventors: |
Sugimori; Masahiro (Nagoya,
JP), Gotou; Kazuya (Toyohashi, JP), Agata;
Akira (Toyohashi, JP), Nishimoto; Yukio (Tokyo,
JP), Taguchi; Masato (Nagoya, JP) |
Assignee: |
Mitsubishi Rayon Co., Ltd.
(Tokyo, JP)
|
Family
ID: |
13557575 |
Appl.
No.: |
09/381,628 |
Filed: |
September 27, 1999 |
PCT
Filed: |
March 25, 1998 |
PCT No.: |
PCT/JP98/01294 |
PCT
Pub. No.: |
WO98/44017 |
PCT
Pub. Date: |
October 08, 1998 |
Foreign Application Priority Data
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Mar 27, 1997 [JP] |
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9-074794 |
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Current U.S.
Class: |
428/36.9;
428/368; 528/88; 528/87; 428/413 |
Current CPC
Class: |
C08G
59/226 (20130101); C08G 59/38 (20130101); C08G
59/26 (20130101); Y10T 428/139 (20150115); Y10T
428/292 (20150115); Y10T 428/31511 (20150401) |
Current International
Class: |
C08G
59/26 (20060101); C08G 59/00 (20060101); C08G
59/22 (20060101); C08G 59/38 (20060101); C08G
018/58 () |
Field of
Search: |
;428/368,36.9,413
;528/87,88,103 ;526/56,58 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1113071 |
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Dec 1995 |
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CN |
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0 256 130 |
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Feb 1988 |
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EP |
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0 296 450 |
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Dec 1988 |
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EP |
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5-43655 |
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Feb 1993 |
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JP |
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5-43657 |
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Feb 1993 |
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JP |
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5-222160 |
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Aug 1993 |
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JP |
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6-56961 |
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Mar 1994 |
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JP |
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8-59793 |
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Mar 1996 |
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JP |
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8-127635 |
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May 1996 |
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JP |
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9-71634 |
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Mar 1997 |
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JP |
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9-100358 |
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Apr 1997 |
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JP |
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Other References
Derwent Abstracts, AN 097226, CA 2 038 786, Sep. 23, 1991..
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Primary Examiner: Watkins, III; William P.
Assistant Examiner: Hon; Sow-Fun
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier
& Neustadt, P.C.
Claims
What is claimed is:
1. An epoxy resin composition, consisting essentially of (A) a
bisphenol A epoxy resin, (B) an epoxy resin having oxazolidone rigs
and having no isocyanate groups, (C) a curing agent, and (D) a
thermoplastic resin which is soluble in a mixture of said bisphenol
A epoxy resin (A) and said epoxy resin (B), said epoxy resin (B)
being an epoxy resin having a structure represented by the
following formula (2): ##STR6## wherein R each independently
represents a hydrogen atom or a methyl group, R.sub.1 to R.sub.4
each independently represent a halogen atom, a hydrogen atom, or an
alkyl group having 1 to 4 carbon atoms, R.sub.5 to R.sub.8 each
independently represent a hydrogen atom or an alkyl group having 1
to 4 carbon atoms, and R.sub.9 represents the following formula (3)
or (4): ##STR7## wherein R'.sub.1 to R'.sub.4 each independently
represent a hydrogen atom or an alkyl group having 1 to 4 on atoms;
##STR8## wherein R'.sub.1 to R'.sub.8 each independently represent
a hydrogen atom or an alkyl group having 1 to 4 carbon atoms and
R'.sub.9 represents a single bond, --CH.sub.2 --,
--C(CH.sub.3).sub.2 --, --SO.sub.2 --, --SO--, --S--, or --O--, and
wherein said bisphenol A epoxy resin (A) is a mixture of a
bisphenol A epoxy resin which has an epoxy equivalent of 300 or
less and is liquid or semisolid at normal temperatures and a
bisphenol A epoxy resin which has an epoxy equivalent of 400 or
more and is solid at normal temperatures.
2. The epoxy resin composition as claimed in claim 1, wherein the
viscosity of said epoxy resin composition of (A)+(B)+(C)+(D) is 100
to 5,000 poises at 60.degree. C.
3. The epoxy resin composition as claimed in claim 1, wherein said
themoplastic resin (D) is a phenoxy resin and/or a
polyvinylformal.
4. The epoxy resin composition as claimed in claim 1, further
comprising (E) other epoxy resin in an amount of 3 to 20% by weight
based on the total of the epoxy resin components comprising the
bisphenol A epoxy resin (A), the epoxy resin (B), and the other
epoxy resin (E).
5. The epoxy resin composition as claimed in claim 1, wherein said
bisphenol A epoxy resin which has an epoxy equivalent of 300 or
less and is liquid or semisolid at normal temperatures is contained
in an amount of 25 to 65% by weight based on the bisphenol A epoxy
resin (A), and the epoxy resin (B) is contained in an amount of 20
to 50% by weight based on a mixture of the bisphenol A epoxy resin
(A) and the epoxy resin (B).
6. The epoxy resin composition as claimed in claim 1, wherein the
composition ratio by weight of the bisphenol A epoxy resin (A), the
epoxy resin (B), and the thermoplastic resin soluble in a mixture
of them (D) is such that (A)/(B)=from 15/1 to 1/5 and
(D)/[(A)+(B)]=from 1/100 to 30/100.
7. The epoxy resin composition as claimed in claim 4, wherein the
sum of the amount of the epoxy resin (B) added and the amount of
the other epoxy resin (E) added is 20 to 50% by weight based on the
total of the epoxy resin components comprising the bisphenol A
epoxy resin (A), the epoxy resin (B), and the other epoxy resin (E)
and the composition ratio by weight of the epoxy resin (B) to the
other epoxy resin (E) is in the range of from 1/3 to 4/1.
8. The epoxy resin composition as claimed in claim 1, wherein the
critical strain energy release rate G.sub.IC is 400 J/m.sup.2 or
more.
9. The epoxy resin composition as claimed in claim 4, wherein the
critical strain energy release rate G.sub.IC is 400 J/m.sup.2 or
more.
10. The epoxy resin composition as claimed in claim 1, wherein said
curing agent (C) is a mixture of dicyandiamide and a urea
compound.
11. The epoxy resin composition as claimed in claim 4, wherein said
curing agent (C) is a mixture of dicyandiamide and a urea
compound.
12. A prepreg, comprising a sheet of reinforcing fibers impregnated
with the epoxy resin composition as claimed in claim 1.
13. A prepreg, comprising a sheet of reinforcing fibers impregnated
with the epoxy resin composition as claimed in claim 4.
14. A prepreg, comprising a sheet of reinforcing fibers impregnated
with the epoxy resin composition as claimed in claim 10.
15. A prepreg, comprising a sheet of reinforcing fibers impregnated
with the epoxy resin composition as claimed in claim 11.
16. A tubular molded article having a plurality of fiber reinforced
plastic layers, wherein the matrix resin composition used in at
least one of sad layers is the epoxy resin composition as claimed
in claim 1.
17. A tubular molded article having a plurality of fiber reinforced
plastic layers, wherein the matrix resin composition used in at
least one of said layers is the epoxy resin composition as claimed
in claim 4.
18. A tubular molded article having a plurality of fiber reinforced
plastic layers, wherein the matrix resin composition used in at
least one of said layers is the epoxy resin composition as claimed
in claim 10.
19. A tubular molded article having a plurality of fiber reinforced
plastic layers, wherein the matrix resin composition used in at
least one of said layers is the epoxy resin composition as claimed
in claim 11.
20. An epoxy resin composition according to claim 1, wherein the
crushing strength will be 200 N or more when it is molded into a
tubular shape.
21. An epoxy resin composition according to claim 1, wherein the
crushing strength will be 240 N or more when it is molded into a
tubular shape.
22. An epoxy resin composition according to claim 1, wherein the
flexural strength in the direction of 90.degree. is 100 MPa or more
when it is formed into a unidirectional laminate.
23. An epoxy resin composition according to claim 1, wherein the
flexural strength in the direction of 90.degree. is 125 MPa or more
when it is formed into a unidirectional laminate.
24. The epoxy resin composition as claimed in claim 1, wherein said
bisphenol A epoxy resin having an epoxy resin equivalent of 300 or
less is contained in an amount of 25 to 65% by weight in the
component (A).
25. The epoxy resin composition as claimed in claim 1, wherein said
viscosity is 300 to 3000 poises at 60.degree. C.
26. The epoxy resin composition as claimed in claim 6, wherein the
composition ratio by weight of the bisphenol A epoxy resin (A), the
epoxy resin (B), and the thermoplastic resin soluble in a mixture
of them (D) is such that (A)/(B)=from 10/1 to 1/3 and
(D)/[(A)+(B)]=from 2/100 to 20/100.
Description
TECHNICAL FIELD
The present invention relates to an epoxy resin composition for
fiber reinforced plastics (abbreviated to FRP in this
specification), a prepreg that is an intermediate material made up
of a combination of an epoxy resin composition and reinforcing
fibers, and a tubular molded article obtained by the use
thereof.
This application is based on a patent application in Japan
(Japanese Patent Application No. Hei 9-74794) and the contents
described in that Japanese application are taken as part of this
description.
BACKGROUND ART
Since epoxy resins after curing are excellent in mechanical
properties, electrical properties, and adhesive properties, they
are widely used in the fields, for example, of sealants for
electronic materials, paints, coating materials, and adhesives.
Further, epoxy resins are important as matrix resins for FRP.
Particularly, when carbon fibers are used as reinforcing fibers for
FRP, epoxy resins are preferably used since they are excellent in
adhesion to carbon fibers. FRP molded articles made up of carbon
fibers and epoxy resins are used in wide range of applications
ranging from general-purpose use in fishing rods, golf club shafts,
etc. to the use in airplanes.
The method for molding FRP molded articles from reinforcing fibers,
such as carbon fibers, and a matrix resin, such as an epoxy resin,
includes several methods. If carbon fibers are used as reinforcing
fibers, a method wherein an intermediate material called a prepreg
prepared by impregnating in advance the reinforcing fibers with a
resin is used for the molding of an FRP molded article is most
widely used. The matrix resin used in this prepreg is required to
be excellent, for example, in adhesion to the reinforcing fibers
and mechanical properties after the molding. Further, the prepreg
is required to have suitable tack in order to make the handling
good. Since epoxy resins can be made to exhibit relatively easily
these properties in a well balanced manner, they are widely used as
a matrix resin for prepregs.
The major application of these FRP molded articles includes tubular
molded articles, such as fishing rods and golf club shafts. Such
tubular molded articles are required to have, as important
properties, flexural strength in the longitudinal direction and
crushing strength in the diametrical direction.
In order to enhance the flexural strength of tubular molded
articles in the longitudinal direction, it is already known that it
is effective to arrange carbon fibers along the length. Further, in
order to improve the crushing strength of tubular molded article in
the diametrical direction, it is already known that it is effective
to arrange carbon fibers circumferentially. However, when a tubular
molded article is reinforced longitudinally and circumferentially
at the same time, the tubular molded article inevitably increases
in weight. An increase in weight of a tubular molded article runs
counter to the recent trend wherein fishing rods and golf club
shafts are made light in weight. Accordingly, there have been
attempted to improve matrix resins to reduce the circumferential
reinforcement of tubular molded articles. However, matrix resins
that can make tubular molded articles light in weight are not now
available.
The present invention aims at providing an epoxy resin composition
for FRP in order to obtain tubular molded articles improved in
flexural strength in the longitudinal direction and crushing
strength in the diametrical direction and a prepreg made of a
combination of that epoxy resin composition for FRP and reinforcing
fibers.
DISCLOSURE OF THE INVENTION
The first subject matter of the present invention resides in an
epoxy resin composition for FRP, characterized in that it comprises
(A) a bisphenol A-type epoxy resin (hereinafter referred to as
component (A)), (B) an epoxy resin having oxazolidone rings
represented by (hereinafter referred to as component (B)), and (C)
a curing agent (hereinafter referred to as component (C)), the
component (B) is an epoxy resin having a structure represented by
the following formula (1): ##STR1##
wherein R represents a hydrogen atom or a methyl group, and the
viscosity measured by the below-described method for measuring
viscosities is 100 to 5,000 poises.
Method for Measuring Viscosities
Use is made of a dynamic viscoelasticity measuring instrument, the
uncured epoxy resin composition for FRP whose viscosity will be
measured is filled between two disk plates 25 mm in diameter that
are positioned with a space of 0.5 mm between them, one of the disk
plates is rotated at a shear rate of 10 radians/sec, and the
viscosity of the epoxy resin is measured under conditions in which
the atmospheric temperature for the measurement is 60.degree.
C.
The second subject matter resides in an epoxy resin composition for
FRP, characterized in that it comprises a component (A), a
component (B), and a component (C), and (D) a thermoplastic resin
that can be dissolved in a mixture of the component (A) and the
component (B) (hereinafter referred to as component (D)) and has a
viscosity of 100 to 5,000 poises measured by the above method.
Further, the third subject matter resides in a prepreg comprising a
sheet of reinforcing fibers impregnated with the above epoxy resin
composition for FRP.
Further the fourth subject matter resides in a tubular molded
article having a plurality of FRP layers, characterized in that the
matrix resin composition used in at least one of the FRP layers is
the above epoxy resin composition for FRP.
And the fifth subject matter resides in an epoxy resin composition
for FRP, characterized in that when the epoxy resin composition for
FRP is molded into a tubular product, the crushing strength is 200
N or more.
In the present invention, "crushing strength" means the crushing
strength, measured by the below-described method, of a tubular
molded article that has an inner diameter of 10 mm, an outer
diameter of 12 mm, and a volume content of fibers of 60+1% and is
prepared by impregnating carbon fibers having an elastic modulus of
220 to 250 GPa with the epoxy resin composition for FRP to make
unidirectional prepregs wherein the carbon fiber areal weight is
150 g/m.sup.2 and the content of the epoxy resin for FRP is 31% by
weight and laminating the unidirectional prepregs so that the
directions of the fibers may be
+45.degree./-45.degree./+45.degree./-45.degree./0.degree./0.degree./
0.degree..
Method for Measuring Crushing Strength
The above-described tubular molded article is cut into a length of
10 mm to obtain a test piece. Using an indenter, a load is exerted
on the test piece and the maximum load at which the test piece is
broken when the indenter is moved at a rate of travel of 5 mm/min
is measured and is designated as the crushing strength.
Further, the sixth subject matter resides in an epoxy resin
composition for FRP, characterized in that when the epoxy resin
composition for FRP is made into a unidirectional laminate, the
flexural strength in a direction of 90.degree. is 110 MPa or
more.
In the present invention, "flexural strength in a direction of
90.degree." means the flexural strength of 90.degree., measured by
the below-described method, of the unidirectional laminate that is
prepared by impregnating carbon fibers having an elastic modulus of
220 to 250 GPa with the epoxy resin composition for FRP to make
unidirectional prepregs wherein the carbon fiber areal weight is
150 g/m.sup.2 and the content of the epoxy resin for FRP is 31% by
weight and laminating fifteen unidirectional prepregs thus made (2
mm in thickness) so that the directions of the fibers may be 0
degrees.
Method for Measuring Flexural Strength in a Direction of
90.degree.
The above-described unidirectional laminate is cut to obtain a test
piece having a length of 60 mm in a direction of 90.degree. to the
direction of the fibers and a width of 10 mm. The maximum load when
the test piece is broken is measured under conditions wherein the
distance between the supports is 32 mm, the diameter of the tip of
the indenter is 3.2 mm, and the rate of travel of the indenter is 2
mm/min and the flexural strength is calculated.
Best Mode for Carrying Out the Invention
As the component (A) of the epoxy resin composition for FRP of the
present invention, those which are generally on the market can be
used. As the component (A), those which when used in the epoxy
resin composition for FRP bring its viscosity to the range
described later may be used. The epoxy equivalent, the molecular
weight, and the state at normal temperatures of the component (A)
are not particularly restricted. Herein, "epoxy equivalent" in the
present invention means the number of grams of the resin containing
epoxy groups in an amount of 1 gram equivalent. As the component
(A), a mixture of a bisphenol A-type epoxy resin having an epoxy
equivalent of 300 or less that is a liquid or a semisolid at normal
temperatures and a bisphenol A-type epoxy resin having an epoxy
equivalent of 400 or more that is a solid at normal temperatures is
preferably used because the strength in a direction of 90.degree.
to the direction of fibers can be exhibited. Further, particularly
preferably, the bisphenol A-type epoxy resin having an epoxy resin
equivalent of 300 or less is contained in an amount of 25 to 65% by
weight in the component (A).
As typical ones of the bisphenol A-type epoxy resin having an epoxy
equivalent of 300 or less that is a liquid or a semisolid at normal
temperatures, EPIKOTE 828 and EPIKOTE 834 manufactured by Yuka
Shell Epoxy K. K. can be mentioned by way of example.
As representative examples of the bisphenol A-type epoxy resin
having an epoxy equivalent of 400 or more that is a solid at normal
temperatures, EPIKOTE 1001, EPIKOTE 1002, EPIKOTE 1004, EPIKOTE
1007, and EPIKOTE 1009 can be mentioned by way of example.
As the component (B) of the epoxy resin composition for FRP of the
present invention, an epoxy resin having oxazolidone rings
represented by the below-shown formula (1) is used. This component
(B) is an essential component for the purpose of the present
invention for obtaining a tubular molded article that exhibits a
high crushing strength. An epoxy resin composition for FRP that
does not contain this component (B) can provide neither a tubular
molded article having both a high crushing strength and a high
flexural strength nor a prepreg good in handleability. Further it
is also necessary to use an epoxy resin containing oxazolidone
rings and epoxy groups in the molecule. A mixture of a compound
containing oxazolidone rings and a compound containing epoxy groups
can provide neither a tubular molded article having both a high
crushing strength and a high flexural strength nor a prepreg good
in handleability. ##STR2## wherein R represents a hydrogen atom or
a methyl group.
As the component (B), an epoxy resin having a structure represented
by the below-shown formula (2) is particularly preferable. This
component (B) can be synthesized by a method disclosed in Japanese
Patent Application, First Publication No. Hei 5-43655 wherein an
epoxy resin and an isocyanate compound are reacted in the presence
of an oxazolidone ring forming catalyst. Further, as commercially
available epoxy resins that can be used as the component (B),
XAC4151 and XAC4152 manufactured by Asahi-Ciba Limited can be
mentioned by way of example. ##STR3## wherein R's each
independently represent a hydrogen atom or a methyl group, R.sub.1
to R.sub.4 each independently represent a halogen atom, a hydrogen
atom, or an alkyl group having 1 to 4 carbon atoms, R.sub.5 to
R.sub.8 each independently represent a hydrogen atom or an alkyl
group having 1 to 4 carbon atoms, and R.sub.9 has the below-shown
formula (3) or the below-shown formula (4). ##STR4## wherein
R'.sub.1 to R'.sub.4 each independently represent a hydrogen atom
or an alkyl group having 1 to 4 carbon atoms. ##STR5## wherein
R'.sub.1 to R'.sub.8 each independently represent a hydrogen atom
or an alkyl group having 1 to 4 carbon atoms and R'.sub.9
represents a single bond, --CH.sub.2 --, --C(CH.sub.3).sub.2 --,
--SO.sub.2 --, --SO--, --S--, or --O--.
As the component (C) of the epoxy resin composition for FRP of the
present invention, any curing agent can be used that is used as a
curing agent for usual epoxy resin compositions. As typical curing
agents, dicyandiamides, ureacompounds, amine compounds, acid
anhydrides, imidazole compounds, phenol compounds, etc. can be
mentioned by way of example. Among others, a combination of a
dicyandiamide and a urea series compound is particularly preferable
because the curability of the epoxy resin composition for FRP and
the balance among the physical properties of the molded article
obtained after the curing are good.
To the epoxy resin composition for FRP of the present invention,
the component (D) can be added. By adding the component (D) to the
epoxy resin composition for FRP, the handleability of the prepreg
is further improved and the properties of the obtainable tubular
molded article, such as the crushing strength, are improved and
stabilized.
As the component (D) of the epoxy resin composition for FRP of the
present invention, a thermoplastic resin that dissolves uniformly
in a mixture of the component (A) with the component (B) is used.
As the component (D), phenoxy resins and polyvinylformal resins are
particularly preferably used. The phenoxy resins are not
particularly restricted and those generally on the market can be
used. For example, PHENOTOHTO YP-50 and PKHP-200 manufactured by
Tohto Kasei Co., Ltd. etc. can be mentioned as typical examples
thereof. As the polyvinylformal resin (hereinafter referred to as
PVF), a resin containing 60% by weight or more of a vinyl formal
moiety with the rest made up of vinylalcohol, vinylacetate, or the
like is used. VINYLEC manufactured by Chisso Corporation can be
mentioned as commercially available typical examples thereof.
The epoxy resin composition for FRP of the present invention is
required to have a viscosity of 100 to 5,000 poises measured by the
below-described method for measuring viscosities. If the viscosity
of the epoxy resin composition for FRP is less than 100 poises at
60.degree. C., the tack becomes too strong or the resin flow at the
time of molding becomes too great, making it impossible to obtain
the intended properties after the molding, which is unpreferable.
Furthermore, if the viscosity of the epoxy resin composition for
FRP is over 5,000 poises, the impregnation with the resin at the
time of formation of a prepreg becomes insufficient, the tack is
lost to too great an extent, or the prepreg becomes hard, making it
impossible to obtain the intended properties after the molding,
which is unpreferable. A more preferable range is from 300 to 3,000
poises.
The viscosity in the present invention is the viscosity measured by
using a dynamic viscoelasticity measuring instrument, such as a
dynamic viscoelasticity measuring instrument RDA-700 manufactured
by Rheometric Scientific F. E. Ltd. in such a manner that the
uncured epoxy resin composition for FRP whose viscosity will be
measured is filled between two disk plates which are 25 mm in
diameter that are positioned with a space of 0.5 mm between them,
one of the disk plates is rotated at a shear rate of 10
radians/sec, and the viscosity of the epoxy resin is measured under
conditions in which the atmospheric temperature for the measurement
is 60.degree. C.
The formulation ratio of the components in the epoxy resin
composition for FRP of the present invention is not particularly
restricted so long as the composition satisfies the above
conditions including the viscosity conditions. If the component (D)
is not contained, the formulation ratio [(A)/(B)] of the component
(A) and the component (B) is preferably in the range of from 9/1 to
3/7 by weight. Further, particularly preferably, the component (B)
accounts for 20 to 50% by weight of the mixture of the component
(A) and the component (B).
Further, when the component (D) is contained, the formulation ratio
[(A)/(B)] of the component (A) and the component (B) is preferably
in the range of from 15/1 to 1/5 by weight and more preferably in
the range of from 10/1 to 1/3 by weight. Further, most preferably,
the component (B) accounts for 7 to 50% by weight of the mixture of
the component (A) and the component (B).
When only a phenoxy resin is used as the component (D) of the epoxy
resin composition for FRP of the present invention, the formulation
ratio {(D)/[(A)+(B)]} of the components in the epoxy resin
composition for FRP is preferably in the range of from 1/100 to
30/100 by weight and more preferably in the range of from 2/100 to
20/100 by weight. Further, when only a polyvinylformal resin is
used as the component (D), the formulation ratio {(D)/[(A)+(B)]} of
the components in the epoxy resin composition for FRP is preferably
in the range of from 1/100 to 20/100 and more preferably in the
range of from 1/100 to 10/100.
To the epoxy resin composition for FRP of the present invention,
another epoxy resin (E) (hereinafter referred to as component (E))
can be added in the range wherein the above formulation ratios are
satisfied. By adding the component (E) to the epoxy resin
composition for FRP, the properties of the tubular molded article,
such as the heat resistance, can further be improved.
As the component (E),. for example, bisphenol F-type, bisphenol
S-type, glycidylamine-type, aminophenol-type, phenolic novolak-
type, and cresol novolak-type epoxy resins, or aliphatic,
cycloaliphatic, and other epoxy resins can be mentioned. Among
others, phenolic novolak-type epoxy resins having a softening point
of 60.degree. C. or more are particularly preferable because they
less adversely affect the balance of the entire properties of the
epoxy resin composition for FRP. As typical examples of phenolic
novolak-type epoxy resins having a softening point of 60.degree. C.
or more, EPICLON N-770 and N-775 manufactured by Dainippon Ink and
Chemicals Inc. can be mentioned.
When the component (E) is added to the epoxy resin composition for
FRP, the component (E) is contained in an amount of 3 to 20% by
weight based on the total of the epoxy resin components consisting
of the component (A), the component (B) and the component (E).
Further, more preferably, the total amount of the component (B)
added and the amount of the component (E) added is 20 to 50% by
weight based on the total of the epoxy resin components consisting
of the component (A), the component (B), and the component (E), and
the composition ratio of the component (B) to the composition (E)
is in the range of from 1/3 to 4/1.
As the epoxy resin composition for FRP of the present invention,
those that are excellent in toughness in addition to the above
conditions are more preferable. Specifically, an epoxy resin
composition for FRP whose G.sub.IC (critical strain energy release
rate) is 400 J/m.sup.2 or more is particularly preferable. Herein,
G.sub.IC can be measured by the compact tension method described in
ASTM-E399.
A sheet of reinforcing fibers is impregnated with the epoxy resin
composition for FRP of the present invention to make them
integrated, thereby forming an intermediate material called a
prepreg.
The reinforcing fibers used in the present invention are not
particularly restricted and use is made of carbon fibers, glass
fibers, aramid fibers, boron fibers, steel fibers, etc. singly or
in combination. Among others, carbon fibers are particularly
preferably used since the mechanical properties after molding are
good.
As the carbon fibers, any of PAN precursor carbon fibers and pitch
precursor carbon fibers can be used. Further, as the carbon fibers,
various carbon fibers different in strength and elastic modulus can
be selected and used according to the purpose.
Further, as the prepreg of the present invention, for example, a
unidirectional prepreg wherein reinforcing fibers are arranged in
one direction, a fabric wherein reinforcing fibers are woven, a
nonwoven fabric of reinforcing fibers, or a prepreg prepared by
impregnating a tow of reinforcing fibers directly with the epoxy
resin composition for FRP of the present invention can be
mentioned.
In the present invention, the sheetlike product wherein reinforcing
fibers are arranged in one direction, the fabric wherein
reinforcing fibers are woven, the nonwoven fabric made up of
reinforcing fibers, the tow of reinforcing fibers, and the like are
simply referred to as a sheet of reinforcing fibers.
The method for impregnating reinforcing fibers with the epoxy resin
composition for FRP of the present invention is not particularly
restricted. As the method for impregnating reinforcing fibers with
the epoxy resin composition for FRP, a method wherein a sheet of
reinforcing fibers is impregnated with the resin from both surfaces
thereof is preferred over a method wherein a sheet of reinforcing
fibers is impregnated with the resin from one surface thereof
because, in the former case, when the sheet is molded into the
tubular molded article intended by the present invention, the
crushing strength and the flexural strength in a direction of
90.degree. are improved.
When the epoxy resin composition for FRP of the present invention
is made into a prepreg, the prepreg has suitable tack and
flexibility and is good in the balance between stability with time
and curability. In particular, when the epoxy resin composition for
FRP of the present invention is made into a unidirectional prepreg
of carbon fibers, such an effect is brought about that the flexural
strength in a direction of 90.degree. to the axes of the fibers of
the molded article is considerably improved. As a result, the
tubular molded article obtained by using the prepreg is improved
considerably in crushing strength and flexural strength. Such an
effect is difficult to obtain using conventional matrix resins and
thus reflects the excellent performance of the epoxy resin
composition of the present invention.
In particular, when a prepreg having a flexural strength of 125 MPa
or more in a direction of 90.degree. to the axes of the fibers is
used, the crushing strength of the obtained tubular molded article
is remarkably improved. Thus, the crushing strength is greatly
affected by flexural strength in a direction of 90.degree. to the
axes of the fibers. Further, the effect of the elastic modulus of
the carbon fibers used is also great and when carbon fibers having
a high elastic modulus are used, generally a favorable crushing
strength is readily be obtained.
Accordingly, when carbon fibers having a high elastic modulus are
used, a good crushing strength is obtained even when the flexural
strength in a direction of 90.degree. to the axes of the carbon
fibers is a little low. In particular, a good crushing strength is
obtained in the case in which the flexural strength in a direction
of 90.degree. to the axes of the fibers and the elastic modulus of
the carbon fibers used satisfy the following relationship:
On the other hand, the lower the resin content in the prepreg is,
the better it is, since the tubular molded article is made lighter
in weight. However, a decrease in the resin content is apt to
result in lowering of the flexural strength in a direction of
90.degree. to the axes of the fibers. Particularly, in the case in
which the resin content is less than 25% by weight, the tendency
for the lowering thereof is increased. Therefore, when a
conventional epoxy resin composition was used as a matrix resin, it
was difficult to secure sufficient crushing strength with the resin
content of the prepreg lowered to make the tubular molded article
light in weight. However, when the epoxy resin composition of the
present invention is used as a matrix resin, even if the resin
content of the prepreg is brought to less than 25% by weight, the
obtained tubular molded article exhibits a crushing strength
improved more than that of the conventional one. Accordingly, the
tubular molded article can be made light in weight with the
properties including crushing strength satisfactorily
maintained.
Particularly, when a tubular molded article is molded using a
prepreg in which the flexural strength in a direction of 90.degree.
to the axes of the fibers, and the resin content of the prepreg and
the elastic modulus of the carbon fibers satisfy the below-given
relationship, the obtained tubular molded article is good in the
balance between the effect of weight reduction and the physical
properties including the crushing strength:
Next, the tubular molded article made of FRP in which the
above-described epoxy resin composition is used is described.
The tubular molded article of the present invention is a tubular
molded article excellent in crushing strength and flexural strength
and is obtained by using the above-described epoxy resin
composition for FRP for the matrix resin of at least one FRP layer
out of a plurality of FRP layers.
This tubular molded article is generally obtained by winding layers
of prepregs around a mandrel and heating and pressing them. It is
required that at least one of these layers consist of the prepreg
which is the third mode of the present invention in order to obtain
the desired properties. Further, if all of the layers consist of
the prepregs of the present invention, excellent properties are
obtained without any problems. However, since respective layers are
generally allocated respective roles, it is not necessarily
required that all the layers consist of the prepregs of the present
invention.
Further, it is possible to use layered prepregs made up of the
prepregs of the present invention and conventional prepregs, which
results in more preferable physical properties in many cases.
Further, the tubular molded article can be obtained by a method
wherein tow prepregs are wound to form layers. As the heating and
pressing method used in molding the tubular molded article,
compression molding in which a mold, such as a metal mold, is used,
autoclave molding, vacuum bag molding, tape lapping molding, etc.
can be mentioned by way of example, but the method is not
necessarily limited to them.
The epoxy resin composition for FRP of the present invention is
preferably such that when the epoxy resin composition is molded
into the tubular molded article, the crushing strength of the
tubular molded article is 200 N or more, the tubular molded article
having an inner diameter of 10 mm, an outer diameter of 12 mm, and
a volume content of fibers of 60+1% and being prepared by
impregnating carbon fibers having an elastic modulus of 220 to 250
GPa with the epoxy resin composition for FRP to make unidirectional
prepregs in which the carbon fiber areal weight is 150 g/m.sup.2
and the content of the epoxy resin for FRP is 31% by weight and
laminating the unidirectional prepregs so that the directions of
the fibers may be
+45.degree./-45.degree./+45.degree./45.degree./0.degree./0.degree./
0.degree.. By defining the crushing strength of the above tubular
molded article as being 200 N or more, the tubular molded article
can be made light in weight by decreasing the number of the
laminated FRP layers. The crushing strength of the tubular molded
article is more preferably 240 N or more.
The epoxy resin composition for FRP of the present invention is
preferably such that when carbon fibers having an elastic modulus
of 220 to 250 GPa are impregnated with this epoxy resin composition
for FRP to make unidirectional prepregs in which the carbon fiber
areal weight is 150 g/m.sup.2 and the content of the epoxy resin
for FRP is 31% by weight and fifteen unidirectional prepregs thus
made are laminated so that the directions of the fibers may be zero
degrees, thereby making a unidirectional laminate (2 mm in
thickness), the flexural strength in a direction of 90.degree. is
110 MPa or more. Thus, by making the flexural strength of the above
unidirectional laminate in a direction of 90.degree. to be 110 MPa
or more, the weight of the tubular molded article can be made light
by decreasing the number of the laminated layers of the FRP layers.
More preferably, the flexural strength of the above unidirectional
laminate in a direction of 90.degree. is 124 MPa or more and
particularly preferably 140 MPa or more.
EXAMPLES
Hereinbelow, the present invention is described more specifically
with reference to Examples.
Abbreviations for compounds, and the test methods in the Examples
are as follows.
Component (A) EP828: a bisphenol A-type epoxy resin, EPIKOTE 828
(epoxy equivalent: 184-194; liquid at normal temperatures),
manufactured by Yuka Shell Epoxy K. K. EP1001: a bisphenol A-type
epoxy resin, EPIKOTE 1001 (epoxy equivalent: 450-500; solid at
normal temperatures), manufactured by Yuka Shell Epoxy K. K.
EP1002: a bisphenol A-type epoxy resin, EPIKOTE 1002 (epoxy
equivalent: 600-700; solid at normal temperatures), manufactured by
Yuka Shell Epoxy K. K. EP1004: a bisphenol A-type epoxy resin,
EPIKOTE 1004 (epoxy equivalent: 875-975; solid at normal
temperatures), manufactured by Yuka Shell Epoxy K. K.
Component (B) XAC4151: an oxazolidone ring containing epoxy resin
manufactured by Asahi-Ciba Limited XAC4152: an oxazolidone ring
containing epoxy resin manufactured by Asahi-Ciba Limited
Component (C) PDMU: phenyldimethyl urea DCMU: dichlorodimethyl urea
DICY: dicyandiamide
Component (D) PY-50: a phenoxy resin, PHENOTOHTO, manufactured by
Tohto Kasei Co., Ltd. VINYLEC E: a polyvinylformal manufactured by
Chisso Corporation VINYLEC K: a polyvinylformal manufactured by
Chisso Corporation
Component (E) N740: a phenol novolak-type epoxy resin, EPICLON N740
(semisolid at normal temperatures), manufactured by Dainippon Ink
and Chemicals Inc. N775: a phenol novolak-type epoxy resin, EPICLON
N775 (softening point: 70-80.degree. C.), manufactured by Dainippon
Ink and Chemicals Inc.
Measurement of Viscosities
Use was made of a dynamic viscoelasticity measuring instrument
RDA-700 manufactured by Rheometric Scientific F. E. Ltd. The
uncured epoxy resin composition for FRP whose viscosity was to be
measured was filled between two disk plates of 25 mm in diameter
and the viscosity of the epoxy resin was measured under conditions
in which the atmospheric temperature for the measurement was
60.degree. C., the space between the disk plates was 0.5 mm, and
the shear rate was 10 radians/sec.
G.sub.IC
In accordance with ASTM-E399, the G.sub.IC was measured by the
compact tension method.
Evaluation of the Handleability of the Prepreg
The prepreg was subjected to a manual sensory test and was
evaluated based on the following criteria: .smallcircle.: both the
tack and the flexibility were good and winding around a mandrel was
quite easy. .DELTA.: flexibility was lacking and the winding around
a mandrel was somewhat difficult. X: the tack was very strong and
winding around a mandrel was difficult.
Measurement of Flexural Strength in a Direction of 90.degree.
Carbon fibers having an elastic modulus of 220 to 250 GPa were
impregnated with the epoxy resin composition for FRP to form
unidirectional prepregs wherein the carbon fiber areal weight was
150 g/m.sup.2 and the content of the epoxy resin for FRP was 31% by
weight. Fifteen layers of the thus made unidirectional prepregs
were placed one on top of the other with the direction of the
fibers being at 0 degrees in order to mold a unidirectional
laminate (2 mm in thickness). This unidirectional laminate was cut
to obtain a test piece having a length of 60 mm in a direction of
90.degree. to the direction of the fibers and a width of 10 mm. The
maximum load necessary to break the test piece was measured under
conditions in which the distance between the supports was 32 mm,
the tip diameter of the indenter was 3.2 mm, and the rate of travel
of the indenter was 2 mm/min and the flexural strength in a
direction of 90.degree. to the axes of the fibers was
calculated.
More specifically, by using a universal testing machine, TENSILON,
available from Orientec Corporation, the test piece measuring 60 mm
in length, 10 mm in width, and 2 mm in thickness was put to test
under such test conditions that the L/D was 16 and the rate of
travel of the indenter having a tip diameter of 3.2 mm was 2
mm/min, wherein L/D represents [the distance between the
supports]/[the thickness of the test piece].
Measurement of flexural Strength in the Direction of the Axes of
the Fibers
In the measurement of the flexural strength in the direction of the
axes of the fibers, a test piece measuring 120 mm in length in the
direction of the axes of the fibers, 10 mm in width, and 2 mm in
thickness was used and tested under such conditions that the rate
of travel of the indenter having a tip diameter of 3.2 mm was 2
mm/min in the same way as in the method for measuring the flexural
strength in a direction of 90.degree., except that L/D was 40.
Measurement of the Crushing Strength
Carbon fibers having an elastic modulus of 220 to 250 GPa were
impregnated with the epoxy resin composition for FRP to form
unidirectional prepregs wherein the carbon fiber areal weight was
150 g/m.sup.2 and the content of the epoxy resin for FRP was 31% by
weight. The unidirectional prepregs were placed one on top the
other so that the directions of the fibers might be
+45.degree./-45.degree./+45.degree./-45.degree./0.degree./0.degree./
0.degree. to mold a tubular molded article having an inner diameter
of 10 mm, an outer diameter of 12 mm and a volume content of fibers
of 60.+-.1%. The tubular molded article was cut into a 10 mm length
to obtain a test piece. A load was applied to the test piece by
using an indenter and the maximum load required until the test
piece broke with the rate of travel of the indenter being 5 mm/min
was measured, the maximum load being designated the crushing
strength.
More specifically, by using a universal testing machine, TENSILON,
available from Orientec Corporation, a load was applied to each of
eight test pieces radially by the indenter to smash it and the
maximum load required until it was broken was measured. The average
value of the eight measurements was designated the crushing
strength.
Four-Point Flexural Test of FRP Tubular Molded Articles
As a test piece, a tubular molded article was prepared in which, in
order to prevent stresses from being concentrated, aluminum rings
having an inner diameter of 11.5 mm, a wall thickness of 2 mm, and
a width of 10 mm were mounted on parts where supports and indenters
would come in contact with the tubular molded article. Using a
universal testing machine, TENSILON, available from Orientec
Corporation, a load was applied to each of such test pieces under
such conditions that the distance between the movable indenters was
500 mm, the distance between the fixed indenters (supports) was 150
mm, and the rate of travel of the indenter was 15 mm/min to measure
the flexural strength. The average value of six such measurements
was designated the flexural strength. Both the measurement of the
crushing strength and the four-point flexural test were carried out
under atmospheric conditions at 21.degree. C. and 50% RH.
Glass Transition Temperature (Tg) of the Cured Resin
By using a dynamic viscoelasticity measuring instrument, RDA-700,
available from Rheometric Scientific F. E. Ltd., a shearing force
was applied to a test piece 60 mm in length, 12 mm in width, and 2
mm in width at a rate of 10 radians/sec with the temperature
increased at 5.degree. C./STEP and the temperature dependence of
the storage modulus was measured. The intersection of the tangent
of the storage modulus curve to the glass state region with the
tangent to the transition region was found as the glass transition
temperature.
Formation of a Shaft for the Measurement of the Torsional
Strength
Each of the shafts for golf clubs was made using the above prepregs
in the following manner.
First, the prepregs were cut in such a manner that when the prepreg
was wound around a tapered mandrel whose small-diameter part had an
outer diameter of 4.6 mm, whose large-diameter part had an outer
diameter of 14.3 mm, and whose length was 1,500 mm, with the
direction of the fibers forming an angle of +45.degree., two layers
would be formed at the opposite ends, and when the prepreg was
wound around it with the direction of the fibers forming an angle
of -45.degree., the same formation would be secured. Then these
prepregs were stuck together with the directions of the fibers
orthogonal to each other. The laminated prepreg was wound around
the mandrel to form an angle layer. Then, a straight layer was
formed by winding three of the prepregs on the above angle layer so
that the above angle might be 0.degree.. Then after a polypropylene
tape having a width of 20 mm and a thickness of 30 .mu.m was wound
thereon with a pitch of 2 mm being secured, it was placed in a
curing oven, where it was heated at a temperature of 145.degree. C.
for 240 min to cure the resin. After the curing, the core was
removed, the polypropylene tape was torn off, a length of 10 mm was
cut off from the small-diameter part and from the large-diameter
part to obtain a shaft for a golf club for the test.
Measurement of the Torsional Strength
The torsional strength of each of the shafts for golf clubs made in
the above manner was measured. The measurement was carried out in
accordance with the torsional test of the qualification standard
and standard certification method of shafts for golf clubs (5 San
No. 2087 (Oct. 4, 1993) approved by Minister of Japanese Ministry
of International Trade & Industry) settled by Product Safety
Society. First, by using a "5KN universal tester" (manufactured by
Mechatronics Engineering Inc.), the small-diameter part of the test
golf club shaft was fixed, torque was applied to the large-diameter
part, and when the shaft broke due to the torsion, this torsion was
designated the torsional strength, and its torsional angle was
designated the break angle. The product of the torsional strength
and the break angle was expressed as the torsional breaking
energy.
Examples 1 to 11 and Comparative Examples 1 to 5
Epoxy resin compositions having the formulations (the values
indicate parts by weight) shown in Tables 1 and 2 were prepared and
each of them was coated to a release paper. Unidirectionally
arranged carbon fibers (TR30G-12L manufactured by Mitsubishi Rayon
Co., Ltd.) were placed on the epoxy resin composition to allow them
to be impregnated with the epoxy resin composition thereby
obtaining a unidirectional prepreg wherein the carbon fiber areal
weight was 150 g/m.sup.2 and the resin content was 31% by weight.
The viscosities of the used epoxy resin compositions and the
results of the evaluation of the handleability of the obtained
prepregs are also shown in Tables 1 and 2.
Then, the obtained prepregs were laminated with the directions of
the carbon fiber arranged and each of the obtained laminates was
subjected to vacuum bag molding under curing conditions at
130.degree. C. for 1 hour to obtain an FRP unidirectional molded
article having the carbon fibers as reinforcing fibers (hereinafter
referred to as unidirectional molded article). With respect to the
obtained unidirectional molded articles, a flexural test in a
direction of the axes of the fibers and in a direction at right
angles to the axes of the fibers, and measurement of the glass
transition temperature were carried out. The results of the
measurements are also shown in Tables 1 and 2.
Further, the obtained prepregs were stuck together with the
directions of the fibers orthogonal to each other to form laminated
prepreg each having two layers. Then, each laminated prepreg was
wounded two times around a mandrel having a diameter of 10 mm so
that the directions of the fibers might be at .+-.45 degrees with
respect to the length of the mandrel to form four prepreg layers
with the two layers having +45 degrees and the two layers having
-45 degrees arranged orthogonally to each other. Then, further, the
prepreg was wound three times around the mandrel with the direction
of the fibers in line with the length of the mandrel to form three
0-degree layers. The molding of the thus formed laminate was
carried out by taping polypropylene molding tape (having a
thickness of 30 .mu.m and a width of 15 mm) to the surface with the
tension being 6.5 kg/15 mm and the pitch being 3 mm and heating in
a curing oven at 130.degree. C. for 1 hour. After the curing, the
mandrel was withdrawn and the tape was unwound to obtain a tubular
molded article having a wall thickness of 1.0 mm and carbon fibers
as reinforcing fibers (hereinafter referred to as tubular molded
article). With respect to the thus obtained tubular molded
articles, the crushing test was carried out. The results are shown
in Tables 1 and 2.
In passing, unidirectional molded articles and tubular molded
articles including those in the following Examples and Comparative
Examples were all prepared so as to have a volume content of carbon
fibers of 60.+-.1% unless otherwise stated.
TABLE 1 Example 1 2 3 4 5 Component (A) EP828 20 30 20 20 30 EP1001
50 30 30 EP1002 30 40 EP1004 Component (B) XAC4151 30 40 50 XAC4152
50 30 Component (C) DICY 5 5 5 5 5 DCMU 4 4 4 4 4 PDMU Component
(E) N740 N775 Viscosity (poises, 60.degree. C.) 1,700 758 702 2,040
898 G.sub.IC of the resin (J/m.sup.2) 640 690 700 710 600
Handleability of the prepreg .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircle. Carbon fibers TR30G TR30G
TR30G TR30G TR30G Flexural strength of the unidirectional In the
1,637 1,627 1,646 1,637 1,656 molded article (MPa) direction of
fibers In a direction 131 133 137 127 132 of 90.degree. Glass
transition temperature (.degree. C.) 122 126 127 125 120 Crushing
strength of the tubular molded article (N) 235 245 255 245 245
Torsional strength (N .multidot. m) 13.1 13.1 13.2 13.0 13.3 Break
angle (.degree.) 101 101 102 100 100 Torsional breaking energy (N
.multidot. m.degree.) 1,323 1,323 1,346 1,300 1,330 Example 6 7 8 9
10 11 Component (A) EP828 50 30 50 30 40 40 EP1001 EP1002 40 50 30
EP1004 30 30 Component (B) XAC4151 20 30 20 70 10 10 XAC4152
Component (C) DICY 5 5 5 5 5 5 DCMU 4 4 4 4 PDMU 2 2 Component (E)
N740 N775 20 Viscosity (poises, 60.degree. C.) 1,600 748 1,330 745
694 600 G.sub.IC of the resin (J/m.sup.2) 510 610 500 720 450 470
Handleability of the prepreg .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle. Carbon
fibers TR30G TR30G TR30G TR30G TR30G TR30G Flexural strength of the
unidirectional In the 1,646 1,676 1,666 1,715 1,637 1,666 molded
article (MPa) direction of fibers In a direction 127 137 132 118
120 131 of 90.degree. Glass transition temperature (.degree. C.)
122 120 122 130 112 132 Crushing strength of the tubular molded
article (N) 225 255 235 206 216 206 Torsional strength (N
.multidot. m) 13.0 13.2 13.1 12.0 12.1 13.1 Break angle (.degree.)
100 102 101 98 98 101 Torsional breaking energy (N .multidot.
m.degree.) 1,300 1,346 1,346 1,176 1,186 1,323
TABLE 2 Comparative Example 1 2 3 4 5 Component (A) EP828 5 5 60 3
EP1001 65 65 47 EP1002 50 EP1004 Component (B) XAC4151 XAC4152 40
50 Component (C) DICY 5 5 5 5 5 DCMU 4 4 4 4 PDMU 2 Component (E)
N740 30 50 30 N775 Viscosity (poises, 60.degree. C.) 901 775 748 93
5,390 G.sub.IC of the resin (J/m.sup.2) 320 280 290 670 730
Handleability of the prepreg .smallcircle. .smallcircle.
.smallcircle. x .DELTA. Carbon fibers TR30G TR30G TR30G TR30G TR30G
Flexural strength of the unidirectional In the 1,637 1,646 1,646
1,686 1,646 molded article (MPa) direction of fibers In a direction
115 111 123 137 73.5 of 90.degree. Glass transition temperature
(.degree. C.) 122 125 123 132 124 Crushing strength of the tubular
molded article (N) 186 176 176 255 167 Torsional strength (N
.multidot. m) 11.8 11.6 12.1 13.2 7.5 Break angle (.degree.) 96 95
98 102 55 Torsional breaking energy (N .multidot. m.degree.) 1,133
1,102 1,186 1,346 413
Examples 12 to 14 and Comparative Examples 6 to 8
Prepared in the same way as in Example 1, except that epoxy resin
compositions having the formulations shown in Tables 3 and 4 were
prepared and HR40-12M manufactured by Mitsubishi Rayon Co., Ltd.
were used as the carbon fibers. The handleability of the prepregs
and the properties of the unidirectional molded articles and
tubular molded articles were evaluated. The results are also shown
in Tables 3 and 4.
TABLE 3 Example 12 13 14 Component (A) EP828 20 20 30 EP1001 50
EP1002 30 40 EP1004 Component (B) XAC4151 30 30 XAC4152 50
Component (C) DICY 5 5 5 DCMU 4 4 PDMU 2 Component (E) N740
Viscosity (poises, 60.degree. C.) 1,700 2,040 748 G.sub.IC of the
resin (J/m.sup.2) 640 710 610 Handleability of the prepreg
.smallcircle. .smallcircle. .smallcircle. Carbon fibers HR40 HR40
HR40 Flexural strength of the unidirectional In the 1,578 1,617
1,617 molded article (MPa) direction of fibers In a direction 99 98
101 of 90.degree. Glass transition temperature (.degree. C.) 122
125 120 Crushing strength of the tubular molded article (N) 186 206
196 Torsional strength (N .multidot. m) 9.9 9.9 9.9 Break angle
(.degree.) 76 76 77 Torsional breaking energy (N .multidot.
m.degree.) 752 752 762
TABLE 4 Comparative Example 6 7 8 Component (A) EP828 5 5 EP1001 65
65 EP1002 50 EP1004 Component (B) XAC4151 XAC4152 Component (C)
DICY 5 5 5 DCMU 4 4 PDMU 2 Component (E) N740 30 50 30 Viscosity
(poises, 60.degree. C.) 901 775 748 G.sub.IC of the resin
(J/m.sup.2) 320 280 290 Handleability of the prepreg .smallcircle.
.smallcircle. .smallcircle. Carbon fibers HR40 HR40 HR40 Flexural
strength of the unidirectional In the 1,588 1,578 1,568 molded
article (MPa) direction of fibers In a direction 80 79 81 of
90.degree. Glass transition temperature (.degree. C.) 122 125 123
Crushing strength of the tubular molded article (N) 137 127 132
Torsional strength (N .multidot. m) 8.2 8.1 8.2 Break angle
(.degree.) 67 66 67 Torsional breaking energy (N .multidot.
m.degree.) 549 535 549
Examples 15 to 38 and Comparative Examples 9 to 20
Prepared in the same way as in Example 1, except that epoxy resin
compositions having the formulations shown in Tables 5 to 8 were
prepared and TR30S-12L manufactured by Mitsubishi Rayon Co., Ltd.
were used as the carbon fibers. The handleability of the prepregs
and the properties of the unidirectional molded articles and
tubular molded articles were evaluated. The results are also shown
in Tables 5 to 8.
TABLE 5 Example 15 16 17 18 19 20 Component (A) EP828 30 30 30 55
45 35 EP1001 EP1002 25 35 45 Component (B) XAC4151 XAC4152 70 70 70
20 20 20 Component (C) DICY 4 4 4 4 4 4 DCMU 4 4 4 4 4 4 PDMU
Component (D) YP-50 6 12 18 8 8 8 Component (E) N740 Viscosity
(poises, 60.degree. C.) 1,100 1,500 3,500 1,500 2,800 4,900
G.sub.IC of the resin (J/m.sup.2) 720 730 750 530 550 540
Handleability of the prepreg .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle. Carbon
fibers TR30S TR30S TR30S TR30S TR30S TR30S Flexural strength of the
unidirectional In the 1,705 1,686 1,676 1,656 1,666 1,656 molded
article (MPa) direction of fibers In a direction 140 138 133 135
137 136 of 90.degree. Glass transition temperature (.degree. C.)
130 129 129 124 123 121 Crushing strength of the tubular molded
article (N) 254.8 245 245 255 255 255 Torsional strength (N
.multidot. m) 13.7 13.4 13.3 13.3 13.4 13.4 Break angle (.degree.)
104 102 101 101 101 102 Torsional breaking energy (N .multidot.
m.degree.) 1,394 1,367 1,343 1,343 1,353 1,367 Example 21 22 23 24
25 26 Component (A) EP828 20 20 50 40 40 40 EP1001 60 30 EP1002 20
40 40 Component (B) XAC4151 30 30 XAC4152 20 50 20 20 Component (C)
DICY 4 4 4 4 4 4 DCMU 4 4 4 4 PDMU 4 4 Component (D) YP-50 8 8 8 8
8 10 Component (E) N740 30 Viscosity (poises, 60.degree. C.) 2,500
3,300 2,000 2,900 2,600 2,100 G.sub.IC of the resin (J/m.sup.2) 520
630 610 540 530 490 Handleability of the prepreg .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. Carbon fibers TR30S TR30S TR30S TR30S TR30S TR30S
Flexural strength of the unidirectional In the 1,676 1,715 1,705
1,695 1,676 1,646 molded article (MPa) direction of fibers In a
direction 134 139 141 138 137 136 of 90.degree. Glass transition
temperature (.degree. C.) 120 126 127 124 123 133 Crushing strength
of the tubular molded article (N) 245 245 255 255 255 245 Torsional
strength (N .multidot. m) 13.3 13.4 13.7 13.4 13.3 13.3 Break angle
(.degree.) 101 102 104 102 102 101 Torsional breaking energy (N
.multidot. m.degree.) 1,343 1,367 1,425 1,367 1,357 1,343
TABLE 6 Comparative Example 9 10 11 12 13 14 Component (A) EP828 25
80 10 10 10 10 EP1001 60 60 40 20 EP1002 55 Component (B) XAC4151
XAC4152 20 20 Component (C) DICY 4 4 4 4 4 4 DCMU 4 4 4 4 4 4 PDMU
Component (D) YP-50 8 2 6 12 6 6 Component (E) N740 30 30 50 70
Viscosity (poises, 60.degree. C.) 6,400 90 2,000 2,800 2,400 2,100
G.sub.IC of the resin (J/m.sup.2) 550 510 300 350 270 260
Handleability of the prepreg .DELTA. x .smallcircle. .smallcircle.
.smallcircle. .smallcircle. Carbon fibers TR30S TR30S TR30S TR30S
TR30S TR30S Flexural strength of the unidirectional In the 1,637
1,685 1,676 1,656 1,656 1,627 molded article (MPa) direction of
fibers In a direction 93 129 108 103 98 70 of 90.degree. Glass
transition temperature (.degree. C.) 120 132 125 123 126 132
Crushing strength of the tubular molded article (N) 186 196 176 176
186 167 Torsional strength (N .multidot. m) 9.8 12.8 11.4 10.5 10.0
7.3 Break angle (.degree.) 77 99 95 85 75 53 Torsional breaking
energy (N .multidot. m.degree.) 755 1,267 1,083 893 750 387
TABLE 7 Example 27 28 29 30 31 32 Component (A) EP828 30 30 30 50
40 30 EP1001 EP1002 30 40 50 Component (B) XAC4151 XAC4152 70 70 70
20 20 20 Component (C) DICY 4 4 4 4 4 4 DCMU 4 4 4 4 4 4 PDMU
Component (D) VINYLEC E 3 6 9 4 4 4 VINYLEC K Component (E) N740
Viscosity (poises, 60.degree. C.) 980 1,400 3,000 1,200 2,500 4,900
G.sub.IC of the resin (J/m.sup.2) 730 730 740 510 570 550
Handleability of the prepreg .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle. Carbon
fibers TR30S TR30S TR30S TR30S TR30S TR30S Flexural strength of the
unidirectional In the 1,715 1,695 1,676 1,646 1,637 1,646 molded
article (MPa) direction of fibers In a direction 144 143 149 145
140 137 of 90.degree. Glass transition temperature (.degree. C.)
129 130 128 126 124 121 Crushing strength of the tubular molded
article (N) 265 255 265 274 265 255 Torsional strength (N
.multidot. m) 13.7 13.5 13.8 13.7 13.8 13.4 Break angle (.degree.)
103 103 104 102 105 101 Torsional breaking energy (N .multidot.
m.degree.) 1,411 1,391 1,435 1,397 1,449 1,353 Example 33 34 35 36
37 38 Component (A) EP828 20 20 50 40 40 40 EP1001 60 30 EP1002 20
40 40 Component (B) XAC4151 30 30 XAC4152 20 50 20 20 Component (C)
DICY 4 4 4 4 4 4 DCMU 4 4 4 4 PDMU 4 4 Component (D) VINYLEC E 4 4
4 4 5 VINYLEC K 5 Component (E) N740 30 Viscosity (poises,
60.degree. C.) 2,200 3,100 1,800 2,700 2,500 2,000 G.sub.IC of the
resin (J/m.sup.2) 520 640 600 540 540 500 Handleability of the
prepreg .smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. .smallcircle. Carbon fibers TR30S TR30S TR30S TR30S
TR30S TR30S Flexural strength of the unidirectional In the 1,656
1,705 1,715 1,705 1,695 1,646 molded article (MPa) direction of
fibers In a direction 141 146 139 138 136 134 of 90.degree. Glass
transition temperature (.degree. C.) 120 125 127 123 123 133
Crushing strength of the tubular molded article (N) 265 265 265 265
255 245 Torsional strength (N .multidot. m) 14.1 13.8 13.5 13.5
13.4 13.3 Break angle (.degree.) 107 104 102 102 101 101 Torsional
breaking energy (N .multidot. m.degree.) 1,509 1,435 1,377 1,377
1,353 1,343
TABLE 8 Comparative Example 15 16 17 18 19 20 Component (A) EP828
25 80 10 10 10 10 EP1001 60 60 40 20 EP1002 55 Component (B)
XAC4151 XAC4152 20 20 Component (C) DICY 4 4 4 4 4 4 DCMU 4 4 4 4 4
4 PDMU Component (D) VINYLEC E 4 2 3 6 3 3 VINYLEC K Component (E)
N740 30 30 50 70 Viscosity (poises, 60.degree. C.) 6,200 90 1,800
2,500 2,200 1,800 G.sub.IC of the resin (J/m.sup.2) 530 520 290 360
270 240 Handleability of the prepreg .DELTA. x .smallcircle.
.smallcircle. .smallcircle. .smallcircle. Carbon fibers TR30S TR30S
TR30S TR30S TR30S TR30S Flexural strength of the unidirectional In
the 1,656 1,705 1,666 1,666 1,656 1,637 molded article (MPa)
direction of fibers In a direction 98 131 113 108 103 78 of
90.degree. Glass transition temperature (.degree. C.) 121 133 124
123 127 134 Crushing strength of the tubular molded article (N) 196
216 206 196 196 206 Torsional strength (N .multidot. m) 10.1 13
11.5 11.4 10.8 7.5 Break angle (.degree.) 82 100 95 94 85 56
Torsional breaking energy (N .multidot. m.degree.) 828 1,300 1,420
1,072 918 420
Examples 39 to 41 and Comparative Examples 21 to 23
Prepared in the same way as in Example 1, except that the carbon
fibers and the epoxy resin compositions shown in Tables 9 and 10
were used. The flexural strength in a direction of 90.degree. of
unidirectional molded articles and the crushing strength of tubular
molded articles were evaluated. The results are also shown in
Tables 9 and 10.
TABLE 9 Example 30 39 40 41 Carbon fibers TR30S MR40 HR40 HS40
Elastic modulus of the carbon fibers (GPa) 235 294 392 451 Epoxy
resin composition Ex. 30 Ex. 30 Ex. 30 Ex. 30 Resin content (wt. %)
30 30 30 30 25,000/the elastic modulus of the carbon fibers 107 85
64 56 Flexural strength in a direction of 90.degree. (MPa) 145 124
103 91 Crushing strength of the tubular molded article (N) 274 255
221 211 Torsional strength (N .multidot. m) 13.7 12.3 10.2 9.0
Break angle (.degree.) 102 93 79 70 Torsional breaking energy (N
.multidot. m.degree.) 1,397 1,144 806 630
TABLE 10 Comparative Example 19 21 22 23 Carbon fibers TR30S MR40
HR40 HS40 Elastic modulus of the carbon fibers (GPa) 235 294 392
451 Epoxy resin composition Comp. Comp. Comp. Comp. Ex. 19 Ex. 19
Ex. 19 Ex. 19 Resin content (wt. %) 30 30 30 30 25,000/the elastic
modulus of the carbon fibers 107 85 64 56 Flexural strength in a
direction of 90.degree. (MPa) 103 80 59 54 Crushing strength of the
tubular molded article (N) 196 162 136 130 Torsional strength (N
.multidot. m) 10.8 8.8 7.0 6.2 Break angle (.degree.) 85 68 53 48
Torsional breaking energy (N .multidot. m.degree.) 918 598 371
298
Example 42 and Comparative Example 24
Prepared in the same way as in Example 1, except that HR40-12M
manufactured by Mitsubishi Rayon Co., Ltd. were used as the carbon
fibers and the compositions of Example 30 and Comparative Example
19 were used as the matrix resin. The flexural strength in a
direction of 90.degree. of unidirectional molded articles and the
crushing strength of tubular molded articles were evaluated. The
results are shown in Table 11.
TABLE 11 Example Comparative Example 40 42 22 24 Carbon fibers HR40
HR40 HR40 HR40 Elastic modulus of the carbon fibers (GPa) 392 392
392 392 Epoxy resin composition Ex. 30 Ex. 30 Comp. Ex. 19 Comp.
Ex. 19 Resin content (wt. %) 30 20 30 20 100,000 .times. the resin
fraction of the prepreg/the 77 51 77 51 elastic modulus of the
carbon fibers Flexural strength in a direction of 90.degree. (MPa)
103 68 59 46 Crushing strength of the tubular molded article (N)
221 147 136 98
Examples 43 to 48 and Comparative Examples 25 and 26
Using the epoxy resin compositions prepared in Example 23 and
Comparative Example 13 and the following two types of carbon
fibers, four types of high-weight prepregs having a prepreg areal
weight of 180 g/m.sup.2 and a resin content of 30% by weight were
produced.
[Used Carbon Fibers]
TR30S-12L: manufactured by Mitsubishi Rayon Co., Ltd.; has an
elastic modulus of 235 GPa
MR40-12M: manufactured by Mitsubishi Rayon Co., Ltd.; has an
elastic modulus of 294 GPa
Further, using the same two types of epoxy resin compositions and
TR30-3L, two types of low-weight prepregs having a prepreg areal
weight of 48 g/m.sup.2 and a resin content of 40% by weight were
produced.
Then the obtained high-weight prepregs and low-weight prepregs were
stuck together such that the directions of the carbon fibers were
orthogonal to each other, thereby obtaining laminated prepregs. The
obtained prepregs were good prepregs wherein there were no
defectively bonded parts and evaluation by touch showed that the
surface was smooth. Each prepreg was wound around a mandrel having
a diameter of 10 mm four times (equivalent to 8 layers) with the
low-weight prepreg inside so that the circumferential direction
might be reinforced. Then molding thereof was carried out in the
same way for the tubular molded article in Example 1, thereby
obtaining a tubular molded article having a length of 600 mm, a
wall thickness of 0.58 mm, and a weight of 18 g. The average volume
content of the carbon fibers of this tubular molded article was
56%.
The flexural test of the obtained molded articles was carried out.
The results are shown in Tables 12 and 13.
TABLE 12 Example 43 44 45 46 Axial reinforcing layer Carbon fibers
TR30S TR30S TR30S MR40 Epoxy resin composition Ex. 23 Comp. Ex. 23
Ex. 23 Ex. 13 Resin content (wt. %) 30 30 30 30 Circumferential
reinforcing layer Carbon fibers TR30 TR30 TR30 TR30 Epoxy resin
composition Ex. 23 Ex. 23 Comp. Ex. 23 Ex. 13 Resin content (wt. %)
40 40 40 40 Four-point flexural properties Strength (MPa) 1,216
1,193 1,193 1,298 Elastic modulus (GPa) 131 131 131 164 Breaking
strain (%) 1.19 1.28 1.28 1.19
TABLE 13 Comparative Example Example 47 48 25 26 Axial reinforcing
layer Carbon fibers MR40 MR40 TR30S MR40 Epoxy resin composition
Comp. Ex. 23 Comp. Comp. Ex. 13 Ex. 13 Ex. 13 Resin content (wt. %)
30 30 30 30 Circumferential reinforcing layer Carbon fibers TR30
TR30 TR30 TR30 Epoxy resin composition Ex. 23 Comp. Comp. Comp. Ex.
13 Ex. 13 Ex. 13 Resin content (wt. %) 40 40 40 40 Four-point
flexural properties Strength (MPa) 1,271 1,199 1,173 1,250 Elastic
modulus (GPa) 163 163 127 155 Breaking strain (%) 1.15 1.01 1.22
1.14
Examples 49 to 53 and Comparative Examples 27 and 28
Tubular molded articles were obtained and evaluated in the same
manner as in Examples 43 to 48 and Comparative Examples 27 and 28,
except that the epoxy resin compositions prepared in Example 30 and
Comparative Example 19 were used.
The results are shown in Tables 14 and 15.
TABLE 14 Example 49 50 51 52 53 Axial reinforcing layer Carbon
fibers TR30S TR30S TR30S MR40 MR40 Epoxy resin composition Ex. 30
Comp. Ex. 30 Ex. 30 Comp. Ex. 19 Ex. 19 Resin content (wt. %) 30 30
30 30 30 Circumferential reinforcing layer Carbon fibers TR30 TR30
TR30 TR30 TR30 Epoxy resin composition Ex. 30 Ex. 30 Comp. Ex. 30
Ex. 30 Ex. 19 Resin content (wt. %) 40 40 40 40 40 Four-point
flexural properties Strength (MPa) 1,231 1,213 1,203 1,308 1,281
Elastic modulus (GPa) 132 132 132 165 164 Breaking strain (%) 1.29
1.29 1.29 1.20 1.16
TABLE 15 Comparative Example 27 28 Axial reinforcing layer Carbon
fibers TR30S MR40 Epoxy resin composition Comp. Comp. Ex. 19 Ex. 19
Resin content (wt. %) 30 30 Circumferential reinforcing layer
Carbon fibers TR30 TR30 Epoxy resin composition Comp. Comp. Ex. 19
Ex. 19 Resin content (wt. %) 40 40 Four-point flexural properties
Strength (MPa) 1,173 1,250 Elastic modulus (GPa) 127 155 Breaking
strain (%) 1.22 1.14
Examples 53 to 58 and Comparative Examples 29 and 30
Tubular molded articles were obtained and evaluated in the same
manner as in Examples 43 to 48 and Comparative Examples 27 and 28,
except that instead of the low-weight prepregs constituting the
inside of the tubular molded articles, a glass scrim cloth prepreg
manufactured by Nitto Boseki Co., Ltd. (Product No.: WP (A) 03 104;
areal weight: 24.5 g/m.sup.2 ; epoxy resin content: 26 wt. %) was
used.
The results are shown in Tables 16 and 17.
TABLE 16 Example 55 56 57 58 Prepreg Carbon fibers TR30S MR40 TR30S
MR40 Epoxy resin Ex. 23 Ex. 23 Ex. 30 Ex. 30 composition Physical
Crushing 220 151 230 165 properties of strength (N) the tubular
Breaking 135 78.7 136 78.9 molded article strength (MPa) Elastic
modulus 7,281 6,840 7,291 6,899 (MPa) Breaking strain 1.86 1.25
1.88 1.14 (%)
TABLE 17 Comparative Example 29 30 Prepreg Carbon fibers TR30S MR40
Epoxy resin composition Comp. Comp. Ex. 13 Ex. 13 Physical Crushing
strength (N) 172 107 properties of Breaking strength (MPa) 86.2
48.8 the tubular Elastic modulus (MPa) 7,193 5,762 molded article
Breaking strain (%) 1.20 0.87
Examples 59 to 61
The epoxy resin compositions in Examples 1, 5 and 9 were coated on
to sheets of release paper and unidirectionally arranged carbon
fibers (TR30G-12L manufactured by Mitsubishi Rayon Co., Ltd.) were
impregnated therewith with the opposite sides of the arranged
carbon fibers being sandwiched between the sheets, thereby
obtaining unidirectional prepregs having a carbon fiber areal
weight of 150 g/m.sup.2 and a resin content of 31% by weight.
The results of the evaluation are shown in Table 18.
TABLE 18 Example 50 60 61 Component (A) EP828 20 30 30 EP1001 50
EP1002 40 EP1004 Component (B) XAC4151 30 70 XAC4152 30 Component
(C) DICY 5 5 5 DCMU 4 4 4 PDMU Component (E) N740 Viscosity
(poises, 60.degree. C.) 1,700 898 745 G.sub.IC of the resin
(J/m.sup.2) 640 600 720 Handleability of the prepreg .smallcircle.
.smallcircle. .smallcircle. Carbon fibers TR30G TR30G TR30G
Flexural strength of the unidirectional In the 1,640 1,662 1,705
molded article (MPa) direction of fibers In a direction 141 143 138
of 90.degree. Glass transition temperature (.degree. C.) 122 132
130 Crushing strength of the tubular molded article (N) 255 260 250
Torsional strength (N .multidot. m) 13.6 13.8 13.3 Break angle
(.degree.) 104 106 103 Torsional breaking energy (N .multidot.
m.degree.) 1,414 1,463 1,370 *1 *2 *3 *1 the same resin composition
as that in Example 1 *2 the same resin composition as that in
Example 5 *3 the same resin composition as that in Example 9
Industrial Applicability
The epoxy resin composition for FRP of the present invention is
better in adhesion to reinforcing fibers than conventional
mainstream epoxy resin compositions whose major compositions are a
bisphenol A-type epoxy resin and a phenolic novolak-type epoxy
resin, and the prepreg thereof is quite excellent in
handleability.
Further, since the FRP tubular molded article in which this epoxy
resin composition is used is excellent in physical flexural
properties and physical crushing properties, fishing rods and
shafts of golf clubs obtained using the FRP tubular molded article
can be made light in weight.
* * * * *